Physical activity and the risk of ovarian cancer: A case-control study in Canada

Global, regional, and national quality of care index of cervical and ovarian cancer: a systematic analysis for the global burden of disease study 1990-2019

BACKGROUND AND OBJECTIVE

Cervical cancer is the most preventable and ovarian cancer is the most lethal gynecological cancer. However, in the world, there are disparities in health care performances resulting in differences in the burden of these cancers. The objective of this study was to compare the health-system quality of care and inequities for these cancers using the Quality of Care Index (QCI).

MATERIAL AND METHODS

The 1990-2019 data of the Global Burden of Disease (GBD) was analyzed to extract rates of incidence, prevalence, mortality, Disability-Adjusted Life Years (DALYs), Years of Life Lost (YLL), and Years of healthy life lost due to disability (YLD) of cervical and ovarian cancer. Four indices were developed as a proxy for the quality of care using the above-mentioned rates. Thereafter, a Principal Components Analysis (PCA) was applied to construct the Quality of Care Index (QCI) as a summary measure of the developed indices.

RESULTS

The incidence of cervical cancer decreased from 1990 to 2019, whereas the incidence of ovarian cancer increased between these years. However, the mortality rate of both cancers decreased in this interval. The global age-standardized QCI for cervical cancer and ovarian cancer were 43.1 and 48.5 in 1990 and increased to 58.5 and 58.4 in 2019, respectively. QCI for cervical cancer and ovarian cancer generally decreased with aging, and different age groups had inequitable QCIs. Higher-income countries generally had higher QCIs for both cancers, but exceptions were also observed.

CONCLUSIONS

Uncovering disparities in cervical and ovarian cancer care across locations, Socio-Demographic Index levels, and age groups necessitate urgent improvements in healthcare systems for equitable care. These findings underscore the need for targeted interventions and prompt future research to explore root causes and effective strategies for narrowing these gaps.

Causal effects of physical activity on the risk of overall ovarian cancer: A Mendelian randomization study

Objective

Inconsistent results were reported on the association of physical activity with ovarian cancer. However, given the limitations of confounders and inverse causation, the validity of the association remained unclear. Therefore, we conducted a two-sample Mendelian randomization analysis, which can effectively avoid the aforementioned interference, to evaluate whether physical activity had a protective effect on ovarian cancer.

Methods

The exposure of interest was physical activity (both self-reported moderate-to-vigorous physical activity and accelerometer-measured physical activity). Summary statistics for physical activity traits were recruited from the UK Biobank (n  =  91,084-377,234), whereas ovarian cancer summary genetic data were obtained from a genome-wide association study involving 25,509 cases and 40,941 healthy individuals. The inverse variance weighted approach was used as the primary Mendelian randomization method. Sensitivity analyses using Mendelian randomization-Egger regression, weighted median, and Mendelian randomization pleiotropy residual sum and outlier were also performed.

Results

The Mendelian randomization analyses indicated that there was no effect of moderate-to-vigorous physical activity (odds ratio, 1.11; 95% confidence interval: 0.66-1.85; P  =  0.702), accelerometer-measured "average acceleration" (0.99 [0.91-1.08]; P  =  0.848), and "overall activity" physical activity (0.97 [ 0.48-1.95]; P  =  0.927) on the risk of overall ovarian cancer. However, "overall accelerations" physical activity (0.18 [0.05-0.64]; P  =  0.008) were suggestively related to a lower risk of endometrioid ovarian cancer.

Conclusions

The Mendelian randomization analyses suggested that physical activity may not help to decrease the risk of overall ovarian cancer.

Lifetime recreational moderate-to-vigorous physical activity and ovarian cancer risk: A case-control study

Results of epidemiologic studies of physical activity and ovarian cancer risk are inconsistent. Few have attempted to measure physical activity over the lifetime or in specific age windows, which may better capture etiologically relevant exposures. We examined participation in moderate-to-vigorous recreational physical activity (MVPA) in relation to ovarian cancer risk. In a population-based case-control study conducted in Montreal, Canada from 2011 to 2016 (485 cases and 887 controls), information was collected on lifetime participation in various recreational physical activities, which was used to estimate MVPA for each participant. MVPA was represented as average energy expenditure over the lifetime and in specific age-periods in units of metabolic equivalents (METs)-hours per week. Odds ratios (OR) and 95% confidence intervals (CI) for the relation between average MVPA and ovarian cancer risk were estimated using multivariable logistic regression models. Confounding was assessed using directed acyclic graphs combined with a change-in-estimate approach. The adjusted OR (95% CI) for each 28.5 MET-hr/week increment of lifetime recreational MVPA was 1.11 (0.99-1.24) for ovarian cancer overall. ORs for individual age-periods were weaker. When examined by menopausal status, the OR (95% CI) for lifetime MVPA was 1.21 (1.00-1.45) for those diagnosed before menopause and 1.04 (0.89-1.21) for those diagnosed postmenopausally. The suggestive positive associations were stronger for invasive ovarian cancers and more specifically for high-grade serous carcinomas. These results do not support a reduced ovarian cancer risk associated with MVPA.

Physical activity, sitting time, and the risk of ovarian cancer: A brief research report employing a meta-analysis of existing

We investigated the associations between physical activity, physical inactivity, and ovarian cancer risk and identified the most effective physical activity intensity and amount to reduce ovarian cancer risk. Thirty-four studies were selected for the present meta-analysis. Physical activity helps decrease ovarian cancer risk. Moderate intensity and low amount of physical activity showed the greatest reduction of ovarian cancer risk and prolonged sitting time had the worst ovarian cancer risk. At least 2 h of moderate physical activity per week and <3 h of sitting time per day provided a preventive effect to ovarian cancer.

Epidemiology of ovarian cancer: a review

Ovarian cancer (OC) is the seventh most commonly diagnosed cancer among women in the world and the tenth most common in China. Epithelial OC is the most predominant pathologic subtype, with five major histotypes that differ in origination, pathogenesis, molecular alterations, risk factors, and prognosis. Genetic susceptibility is manifested by rare inherited mutations with high to moderate penetrance. Genome-wide association studies have additionally identified 29 common susceptibility alleles for OC, including 14 subtype-specific alleles. Several reproductive and hormonal factors may lower risk, including parity, oral contraceptive use, and lactation, while others such as older age at menopause and hormone replacement therapy confer increased risks. These associations differ by histotype, especially for mucinous OC, likely reflecting differences in etiology. Endometrioid and clear cell OC share a similar, unique pattern of associations with increased risks among women with endometriosis and decreased risks associated with tubal ligation. OC risks associated with other gynecological conditions and procedures, such as hysterectomy, pelvic inflammatory disease, and polycystic ovarian syndrome, are less clear. Other possible risk factors include environmental and lifestyle factors such as asbestos and talc powder exposures, and cigarette smoking. The epidemiology provides clues on etiology, primary prevention, early detection, and possibly even therapeutic strategies.

Epidemiology of ovarian cancer: a review

Ovarian cancer (OC) is the seventh most commonly diagnosed cancer among women in the world and the tenth most common in China. Epithelial OC is the most predominant pathologic subtype, with five major histotypes that differ in origination, pathogenesis, molecular alterations, risk factors, and prognosis. Genetic susceptibility is manifested by rare inherited mutations with high to moderate penetrance. Genome-wide association studies have additionally identified 29 common susceptibility alleles for OC, including 14 subtype-specific alleles. Several reproductive and hormonal factors may lower risk, including parity, oral contraceptive use, and lactation, while others such as older age at menopause and hormone replacement therapy confer increased risks. These associations differ by histotype, especially for mucinous OC, likely reflecting differences in etiology. Endometrioid and clear cell OC share a similar, unique pattern of associations with increased risks among women with endometriosis and decreased risks associated with tubal ligation. OC risks associated with other gynecological conditions and procedures, such as hysterectomy, pelvic inflammatory disease, and polycystic ovarian syndrome, are less clear. Other possible risk factors include environmental and lifestyle factors such as asbestos and talc powder exposures, and cigarette smoking. The epidemiology provides clues on etiology, primary prevention, early detection, and possibly even therapeutic strategies.

Epidemiology of ovarian cancer: a review

Ovarian cancer (OC) is the seventh most commonly diagnosed cancer among women in the world and the tenth most common in China. Epithelial OC is the most predominant pathologic subtype, with five major histotypes that differ in origination, pathogenesis, molecular alterations, risk factors, and prognosis. Genetic susceptibility is manifested by rare inherited mutations with high to moderate penetrance. Genome-wide association studies have additionally identified 29 common susceptibility alleles for OC, including 14 subtype-specific alleles. Several reproductive and hormonal factors may lower risk, including parity, oral contraceptive use, and lactation, while others such as older age at menopause and hormone replacement therapy confer increased risks. These associations differ by histotype, especially for mucinous OC, likely reflecting differences in etiology. Endometrioid and clear cell OC share a similar, unique pattern of associations with increased risks among women with endometriosis and decreased risks associated with tubal ligation. OC risks associated with other gynecological conditions and procedures, such as hysterectomy, pelvic inflammatory disease, and polycystic ovarian syndrome, are less clear. Other possible risk factors include environmental and lifestyle factors such as asbestos and talc powder exposures, and cigarette smoking. The epidemiology provides clues on etiology, primary prevention, early detection, and possibly even therapeutic strategies.

Recreational physical activity and ovarian cancer risk in African American women

The literature on recreational physical activity (RPA) and ovarian cancer risk is inconclusive and most studies of RPA and ovarian cancer have been conducted in white populations. This study is the first to investigate the association between RPA and ovarian cancer in an exclusively African American (AA) population. We analyzed data from an ongoing U.S. population-based, case-control study of AA women, which included 393 women recently diagnosed with invasive epithelial ovarian cancer (IEOC) and 611 controls. A baseline interview assessed RPA frequency, intensity, and duration. Each RPA intensity was assigned a metabolic equivalent of task (MET) value and MET-min/week were calculated. Unconditional multivariable logistic regression was performed to investigate associations between RPA and IEOC risk. Compared with sedentary women, predominantly mild intensity RPA was significantly inversely associated with IEOC risk for women reporting above median (>297) MET-min/week (odds ratio [OR] = 0.52; 95% confidence interval [CI]: 0.34, 0.78) and nonsignificantly for <297 MET-min/week (OR = 0.71; 95% CI: 0.44, 1.12). Predominantly moderate intensity RPA was associated with significantly increased risk for women reporting above median (>540) MET-min/week (OR = 1.51; 95% CI: 1.03, 2.23). Predominantly strenuous intensity RPA was nonsignificantly associated with lower IEOC risk for women reporting above median (>1800) MET-min/week (OR = 0.72; 95% CI: 0.33, 1.57). The inverse associations for mild and strenuous intensity RPA were most pronounced in obese women (body mass index >30 kg/m(2) ). The findings that mild and strenuous RPA may reduce the risk of IEOC particularly among obese women are difficult to reconcile with the increased risk observed for moderate RPA. Further research is warranted to determine whether these findings are genuine and, if so, their mechanistic basis.

Epithelial ovarian cancer and recreational physical activity: A review of the epidemiological literature and implications for exercise prescription

Despite the publication of two dozen observational epidemiological studies investigating the association between recreational physical activity (RPA) and epithelial ovarian cancer (EOC) risk and survival over the past two decades, taken collectively, data from retrospective and prospective studies are mixed and remain inconclusive.

OBJECTIVE

Our primary purpose was to conduct a careful review and summary of the epidemiological literature depicting the association between EOC and RPA in the framework of identifying factors which may be impeding our ability to observe consistent associations in the literature. Secondly, in the backdrop of the more broad scientific evidence regarding the benefits of RPA, we provide a summary of guidelines for practitioners to utilize in the context of exercise prescription for cancer patients, including a discussion of special considerations and contraindications to exercise which are unique to EOC patients and survivors.

METHODS

We performed a comprehensive literature search via PubMed to identify epidemiologic investigations focused on the association between RPA and EOC. To be included in the review, studies had to assess RPA independently of occupational or household activities.

RESULTS

In total, 26 studies were identified for inclusion. Evidence of a protective effect of RPA relative to EOC risk is more consistent among-case control studies, with the majority of studies demonstrating significant risk reductions between 30 and 60% among the most active women. Among cohort studies, half yielded no significant associations, while the remaining studies provided mixed evidence of an association.

CONCLUSIONS

Given the limitations identified in the current body of literature, practitioners should not rely on inconclusive evidence to dissuade women from participating in moderate or vigorous RPA. Rather, emphasis should be placed on the greater body of scientific evidence which has demonstrated that RPA results in a plethora of health benefits that can be achieved in all populations, including those with cancer.

Recreational physical activity and risk of ovarian cancer: a meta-analysis

Our aim was to access the association between recreational physical activity (RPA) and risk of ovarian cancer (OC). The studies were retrieved from the PubMed and Embase databases up to February 20th, 2014. Risk ratios (OR) and 95% confidence intervals (CI) were used to estimate effect sizes. Random-effects or fixed-effects models were used to pool the data. The trim and fill method was applied for sensitivity analysis. Begg's rank correlation test and Egger's regression asymmetry test were employed to assess the publication bias. A total of 6 studies (435398 participants including 2983 OC patients) were included in this meta-analysis. The overall estimate indicated that there was weakly inverse association between RPA and OC risk (RR=0.90, 95%CI: 0.72-1.12, p=0.335). Meanwhile, for prospective cohort studies, a result consistent with the overall estimate was obtained (RR=1.12, 95% CI: 0.88-1.42, p=0.356). However, for case control studies, the pooled estimate of RR was 0.76 (95%CI: 0.64-0.90, p=0.002), indicating a clear significant association between RPA and OC risk. In addition, the sensitivity analysis indicated a significant link between RPA and risk of OC after removing Lahmann's study (RR=0.80, 95% CI: 0.68-0.93, p=0.004). No significant publication bias was found (Begg's test: p=1.00; Egger's test: p=0.817). In conclusion, our meta-analysis indicated a weakly inverse relationship between RPA and the occurrence of OC.

Physical activity in different periods of life, sedentary behavior, and the risk of ovarian cancer in the NIH-AARP diet and health study

BACKGROUND

Physical activity and sedentary behavior may influence ovarian cancer risk, but clear evidence is lacking.

METHODS

We prospectively investigated the relations of self-reported physical activity and sedentary behavior to ovarian cancer incidence in a cohort of 148,892 U.S. women ages 50-71 years at baseline (1995-1996), who were followed through 2006. Multivariate Cox proportional hazard models were used to estimate relative risks (RR) and 95% confidence intervals (CI). We also conducted analysis by hormone use, body mass index (BMI), and cancer subtype.

RESULTS

We identified 753 incident epithelial ovarian cancers. Overall, neither physical activity nor sedentary behavior at baseline was associated with ovarian cancer risk. Compared with women who never or rarely engaged in vigorous physical activity in the past year, women who reported more than 5 times/week of vigorous physical activity had an RR of 1.05 (95% CI, 0.84-1.32). Women who sat 7+ hours/day had an RR of 1.05 (95% CI, 0.80-1.37) compared with those reporting <3 hours of sitting. The associations were not modified by hormone use or BMI and were similar for both serous and non-serous subtypes.

CONCLUSIONS

Physical activity and sedentary behavior in middle and older ages were not associated with ovarian cancer risk.

IMPACT

We found no clear support for a role of physical activity and sedentary behavior in ovarian cancer risk.

Physical activity in patients with advanced-stage cancer: a systematic review of the literature

The importance of physical activity for chronic disease prevention and management has become generally well accepted. The number of research interventions and publications examining the benefits of physical activity for patients with cancer has been rising steadily. However, much of that research has focused on the impact of physical activity either prior to or early in the cancer diagnosis, treatment, and survivorship process. Research focusing on the effects of physical activity, specifically for patients with advanced-stage cancer and poorer prognostic outcomes, has been addressed only recently. The purpose of this article is to examine the state of the science for physical activity in the advanced-stage disease subset of the cancer population. Exercise in a variety of intensities and forms, including yoga, walking, biking, and swimming, has many health benefits for people, including those diagnosed with cancer. Research has shown that, for people with cancer (including advanced-stage cancer), exercise can decrease anxiety, stress, and depression while improving levels of pain, fatigue, shortness of breath, constipation, and insomnia. People diagnosed with cancer should discuss with their oncologist safe, easy ways they can incorporate exercise into their daily lives.

Ovarian cancer: etiology, risk factors, and epidemiology

Little is known regarding the early aspects of ovarian carcinogenesis. As a consequence, the identification of women at risk for the disease is based primarily on clinical grounds, with family history being the most important risk factor. In this review, we will discuss the various hypotheses regarding ovarian etiology and pathogenesis. In addition, we will discuss the epidemiology of ovarian cancer, including hereditary, reproductive, hormonal, inflammatory, dietary, surgical, and geographic factors that influence ovarian cancer risk.

Recreational physical activity and ovarian cancer risk and survival

PURPOSE

Physical activity may influence ovarian cancer risk and outcomes through effects on ovulation, inflammatory markers, and other processes. We examined associations between self-reported physical activity and ovarian cancer risk and survival in a population-based, case-control study in North Carolina.

METHODS

The analyses involved 638 epithelial ovarian cancer cases and 683 controls recruited between 1999-2008. Logistic regression analyses were used to assess ovarian cancer risk in relation to reported average physical activity at various time periods. Kaplan-Meier analyses and proportional hazards modeling were used to assess associations between physical activity and survival among ovarian cancer cases.

RESULTS

Modestly reduced risks for ovarian cancer were observed in some categories of physical activity, but there were no consistent patterns of greater reductions in risk with higher activity levels. Physical activity before diagnosis was not significantly related to ovarian cancer survival overall, but survival was better for women who reported greater than 2 hours of activity/week as compared to those reporting less than 1 hour/week among women who were non-obese (multivariable Hazard ratio = 0.69, 95% confidence interval: 0.47-1.00).

CONCLUSIONS

Our data provide weak evidence in support of beneficial effects of physical activity on ovarian cancer risk and survival, but results should be interpreted cautiously because of the lack of a clear dose response relation with higher levels of exercise and the likely misclassification of self-reported activity.

State of the epidemiological evidence on physical activity and cancer prevention

BACKGROUND

Physical activity is a modifiable lifestyle risk factor that has the potential to reduce the risk of most major cancer sites.

METHODS

We examined the strength, consistency, dose-response and biological plausibility of an association between physical activity and risk of colon, breast, endometrium, lung, prostate, ovarian, gastric, rectal, pancreatic, bladder, testicular, kidney and haematological cancers. We also estimated the population-attributable risk (PAR) for physical inactivity and cancer in 15 European countries.

RESULTS

There is convincing or probable evidence for a beneficial effect of physical activity on the risk of colon, breast and endometrial cancers. The evidence is weaker for ovarian, lung and prostate cancers and generally either null or insufficient for all remaining cancers. Several hypothesised biological mechanisms include a likely effect of physical activity on insulin resistance, body composition, sex steroid hormones and a possible effect on vitamin D, adipokines, inflammation and immune function. Somewhere between 165,000 and 330,000 cases of the six major cancers (breast, colon, lung, prostate, endometrium and ovarian) could have been prevented in 2008 in Europe alone if the population had maintained sufficient levels of physical activity.

CONCLUSION

There is strong and consistent evidence that physical activity reduces the risk of several of the major cancer sites, and that between 9% and 19% of cancer cases could be attributed to lack of sufficient physical activity in Europe. Public health recommendations for physical activity and cancer prevention generally suggest 30-60 min of moderate or vigorous-intensity activity done at least 5d per week.

Physical activity and gynecologic cancer prevention

This chapter reviews the findings from epidemiologic studies of the associations of physical activity with gynecologic cancers, including those of the endometrium, ovaries, and cervix, and the biologic mechanisms mediating the associations. The epidemiologic evidence to date suggests that physical activity probably protects against endometrial cancer, with a risk reduction of about 20-30% for those with the highest levels of physical activity compared to those with the lowest levels, and that light to moderate physical activity including housework, gardening, or walking for transportation may reduce risk. The role of physical activity in ovarian cancer development remains uncertain, as findings from these studies have been inconsistent with about half the studies suggesting physical activity modestly decreases risk and about half the studies suggesting no association. A recent meta-analysis of studies examining recreational physical activity with ovarian cancer risk estimated a 20% reduced risk for the most active versus least active women. There is mounting evidence that sedentary behaviors such as sitting time probably increase risk of endometrial and ovarian cancers. Overall, there is insufficient evidence to draw a conclusion on a possible role of physical activity in the development of cervical cancer, although a modest influence on risk is possible through effects on sex steroid hormones and immune function. The biologic evidence provides strong support for a protective role of physical activity on cancer of the endometrium, and moderate support for cancer of the ovaries, as these cancers have a strong hormonal etiology. The more established biologic mechanisms that are supported by epidemiologic and experimental data involve endogenous sex hormone levels, insulin-mediated pathways, and maintenance of energy balance.In this chapter, we will discuss the evidence for an association of physical activity with gynecologic cancers including those of the endometrium, ovaries, and cervix. Cancers of the endometrium and ovaries have a strong hormonal etiology (Risch 1998; Kaaks et al. 2002; Lukanova and Kaaks 2005), and physical activity has been postulated as a potential modifiable risk factor for prevention of these cancers because it can influence circulating hormone levels, energy balance, and insulin-mediated pathways that are thought to be important mediators underlying the associations. Few studies have evaluated the association of physical activity with cervical cancer because the main causal factor is infection with certain types of human papillomavirus (HPV), although other hormonal and immune factors are also thought to play a role (Smith et al. 2003; Waggoner 2003). We review the findings from epidemiologic studies that have examined the associations of physical activity with gynecologic cancers, and the biologic mechanisms that might mediate the associations.

Occupational sitting and health risks: a systematic review

CONTEXT

Emerging evidence suggests that sedentary behavior (i.e., time spent sitting) may be negatively associated with health. The aim of this study was to systematically review the evidence on associations between occupational sitting and health risks.

EVIDENCE ACQUISITION

Studies were identified in March-April 2009 by literature searches in PubMed, PsycINFO, CENTRAL, CINAHL, EMBASE, and PEDro, with subsequent related-article searches in PubMed and citation searches in Web of Science. Identified studies were categorized by health outcome. Two independent reviewers assessed methodologic quality using a 15-item quality rating list (score range 0-15 points, higher score indicating better quality). Data on study design, study population, measures of occupational sitting, health risks, analyses, and results were extracted.

EVIDENCE SYNTHESIS

43 papers met the inclusion criteria (21% cross-sectional, 14% case-control, 65% prospective); they examined the associations between occupational sitting and BMI (n=12); cancer (n=17); cardiovascular disease (CVD, n=8); diabetes mellitus (DM, n=4); and mortality (n=6). The median study-quality score was 12 points. Half the cross-sectional studies showed a positive association between occupational sitting and BMI, but prospective studies failed to confirm a causal relationship. There was some case-control evidence for a positive association between occupational sitting and cancer; however, this was generally not supported by prospective studies. The majority of prospective studies found that occupational sitting was associated with a higher risk of DM and mortality.

CONCLUSIONS

Limited evidence was found to support a positive relationship between occupational sitting and health risks. The heterogeneity of study designs, measures, and findings makes it difficult to draw definitive conclusions at this time.

Risk factors for epithelial ovarian cancer by histologic subtype

Previous epidemiologic studies suggest that the major histologic subtypes of epithelial ovarian cancer may have different risk factor profiles; however, no known prospective study has systematically examined differences in risk by subtype. The authors used Cox proportional hazards regression, stratified by histologic subtype and time period, to examine the association between ovarian cancer risk factors and incidence of serous invasive, endometrioid, and mucinous ovarian cancers in the US Nurses' Health Study (1976-2006) and Nurses' Health Study II (1989-2005). For each exposure, they calculated P-heterogeneity using a likelihood ratio test comparing models with separate estimates for the 3 subtypes versus a single estimate across subtypes. Analysis included 221,866 women and 721 cases with the histologies of interest (496 serous invasive, 139 endometrioid, 86 mucinous). In analyses of reproductive/hormonal exposures, the associations with age, duration of breastfeeding, age at natural menopause, and duration of estrogen use differed significantly by subtype (all P-heterogeneity < or =0.05). The associations with several nonreproductive exposures also appeared to vary by subtype, but only the association with smoking differed significantly (P-heterogeneity = 0.03). Results suggest that associations with several ovarian cancer risk factors vary by subtype, and these differences are consistent with known similarities between each major histologic subtype and its normal tissue counterpart.

Recreational physical activity and risk of epithelial ovarian cancer

BACKGROUND

Physical activity may influence ovarian cancer risk through hormonal, inflammatory, or immune-mediated processes or by suppressing ovulation. In a population-based case-control study of epithelial ovarian cancer, we assessed risk associated with recreational physical activity with a focus on characterizing risk within histologic subtypes.

METHODS

Information was collected during in-person interviews with 812 women with ovarian cancer diagnosed in western Washington State from 2002-2005 and 1,313 controls. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs). Exercise was assessed according to the average hours and metabolic equivalent (MET)-hours per week and the number of years in which regular recreational activity occurred.

RESULTS

Relative to women who reported no regular exercise throughout adulthood, the overall risk of invasive, but not borderline, ovarian cancer was reduced among more active women. Reductions in risk of invasive disease were most evident among women with the greatest frequency of high-intensity activity during adulthood. For serous invasive cancer, women in the uppermost category of MET-hours per week of recreational activity in adulthood had 60% the risk of inactive women (95% CI 0.4-0.9), whereas this level of activity was associated with more than a doubling in risk of endometrioid and clear cell invasive tumors.

CONCLUSIONS

Our findings are compatible with an overall reduction in risk of invasive epithelial ovarian cancer associated with recreational activity but suggest that this association may differ in women with different histologic types of disease. Inconsistent findings across studies that have considered histologic type indicate that this issue is not yet resolved.

Recreational physical activity and steroid hormone levels in postmenopausal women

Recreational physical activity has been both positively and inversely associated with cancer risk for postmenopausal women, acting presumably through hormonal mechanisms. Relatively little is known about the effects of exercise on postmenopausal steroid hormone levels. The authors evaluated the association between recreational activity and plasma steroid hormones among 623 US healthy, postmenopausal women in the Nurses' Health Study not using exogenous hormones at the time of blood draw (1989-1990). Participants self-reported recreational physical activity by questionnaire in 1986, 1988, and 1992. Plasma samples were assayed for estrogens, androgens, and sex hormone-binding globulin. Geometric mean hormone levels adjusted and not adjusted for body mass index were calculated. In general, estrogen and androgen levels were lower in the most- and the least-active women compared with those reporting moderate activity, suggesting a U-shaped relation. For example, estrone sulfate levels in quintiles 1-5 of metabolic equivalent task-hours were 197, 209, 222, 214, and 195 pg/mL, respectively. Tests for nonlinearity using polynomial regression were significant for several estrogens, androgens, and sex hormone-binding globulin (2-sided P <or= 0.01). These results suggest the possibility of a nonlinear relation between recreational physical activity and hormone levels in postmenopausal women.

Energy intake, physical activity, energy balance, and cancer: epidemiologic evidence

Energy intake, physical activity, and obesity are modifiable lifestyle factors. This chapter reviews and summarizes the epidemiologic evidence on the relation of energy intake, physical activity, and obesity to cancer. High energy intake may increase the risk of cancers of colon-rectum, prostate (especially advanced prostate cancer), and breast. However, because physical activity, body size, and metabolic efficiency are highly related to total energy intake and expenditure, it is difficult to assess the independent effect of energy intake on cancer risk. There are sufficient evidences to support a role of physical activity in preventing cancers of the colon and breast, whereas the association is stronger in men than in women for colon cancer and in postmenopausal than in premenopausal women for breast cancer. The evidence also suggests that physical activity likely reduces the risk of cancers of endometrium, lung, and prostate (to a lesser extent). On the other hand, there is little or no evidence that the risk of rectal cancer is related to physical activity, whereas the results have been inconsistent regarding the association between physical activity and the risks of cancers of pancreas, ovary and kidney. Epidemiologic studies provide sufficient evidence that obesity is a risk factor for both cancer incidence and mortality. The evidence supports strong links of obesity with the risk of cancers of the colon, rectum, breast (in postmenopausal women), endometrium, kidney (renal cell), and adenocarcinoma of the esophagus. Epidemiologic evidence also indicates that obesity is probably related to cancers of the pancreas, liver, and gallbladder, and aggressive prostate cancer, while it seems that obesity is not associated with lung cancer. The role of obesity in other cancer risks is unclear.

Prospective study of physical activity and the risk of ovarian cancer

BACKGROUND

Available studies on physical activity and ovarian cancer have produced inconsistent findings, with some previous studies reporting a positive association between vigorous physical activity and ovarian cancer risk.

METHODS

We prospectively investigated the relations of self-reported moderate and vigorous physical activity to ovarian cancer in a cohort of 96,216 US women aged 51-72 years at baseline, followed from 1996-1997 to 31 December 2003.

RESULTS

During seven years of follow-up, we documented 309 cases of epithelial ovarian carcinoma. In analyses adjusted for age, the relative risks (RRs) of ovarian cancer for individual and joint combinations of moderate and vigorous physical activity such as entirely inactive, neither moderate nor vigorous physical activity, moderate physical activity only, vigorous physical activity only, and both moderate and vigorous physical activity were 0.88, 1.0 (reference), 0.89, 1.05, and 1.08 (95% confidence interval (CI) = 0.81-1.43, respectively. After multivariate adjustment, the relation was essentially unchanged (RR comparing women with both moderate and vigorous physical activity to those with neither moderate nor vigorous physical activity = 1.10; 95% CI = 0.82-1.48). The null association between physical activity and ovarian cancer persisted in subgroups of women as defined by body mass index, parity, oral contraceptive use, menopausal hormone therapy, family history of ovarian cancer, and other variables (all p values for interaction >0.05).

CONCLUSIONS

Neither moderate nor vigorous physical activity showed a statistically significant association with ovarian cancer in this large cohort of women.

Recreational physical activity and epithelial ovarian cancer: a case-control study, systematic review, and meta-analysis

It remains unclear whether physical activity is associated with epithelial ovarian cancer risk. We therefore examined the association between recreational physical activity and risk of ovarian cancer in a national population-based case-control study in Australia. We also systematically reviewed all the available evidence linking physical activity with ovarian cancer to provide the best summary estimate of the association. The case-control study included women ages 18 to 79 years with a new diagnosis of invasive (n=1,269) or borderline (n=311) epithelial ovarian cancer identified through a network of clinics, physicians, and state cancer registries throughout Australia. Controls (n=1,509) were randomly selected from the national electoral roll and were frequency matched to cases by age and state. For the systematic review, we identified eligible studies using Medline, the ISI Science Citation Index, and manual review of retrieved references, and included all case-control or cohort studies that permitted assessment of an association between physical activity (recreational/occupational/sedentary behavior) and histologically confirmed ovarian cancer. Meta-analysis was restricted to the subset of these studies that reported on recreational physical activity. In our case-control study, we observed weakly inverse or null associations between recreational physical activity and risk of epithelial ovarian cancer overall. There was no evidence that the effects varied by tumor behavior or histologic subtype. Twelve studies were included in the meta-analysis, which gave summary estimates of 0.79 (95% confidence interval, 0.70-0.85) for case-control studies and 0.81 (95% confidence interval, 0.57-1.17) for cohort studies for the risk of ovarian cancer associated with highest versus lowest levels of recreational physical activity. Thus, pooled results from observational studies suggest that a modest inverse association exists between level of recreational physical activity and the risk of ovarian cancer.

Advanced pubertal status at age 11 and lower physical activity in adolescent girls

OBJECTIVE

To examine the relationship between pubertal timing and physical activity.

STUDY DESIGN

A longitudinal sample of 143 adolescent girls was assessed at ages 11 and 13 years. Girls' pubertal development was assessed at age 11 with blood estradiol levels, Tanner breast staging criteria, and parental report of pubertal development. Girls were classified as early maturers (n = 41) or later maturers (n = 102) on the basis of their scores on the 3 pubertal development measures. Dependent variables measured at age 13 were average minutes/day of moderate to vigorous and vigorous physical activity as measured by the ActiGraph accelerometer.

RESULTS

Early-maturing girls had significantly lower self-reported physical activity and accumulated fewer minutes of moderate to vigorous and vigorous physical activity and accelerometer counts per day at age 13 than later maturing girls. These effects were independent of differences in percentage body fat and self-reported physical activity at age 11.

CONCLUSION

Girls experiencing early pubertal maturation at age 11 reported lower subsequent physical activity at age 13 than their later maturing peers. Pubertal maturation, in particular early maturation relative to peers, may lead to declines in physical activity among adolescent girls.

Risk factors for ovarian cancer histotypes

To analyse the risk factors for different histologic types of ovarian cancer, we conducted a case-control study. The cases included 750 women with incident, histologically confirmed invasive epithelial ovarian cancer subdivided into: 493 serous, 81 mucinous, 78 endometrioid, and 98 other histologies. The controls included 2411 women admitted to the same hospitals as cases. The odds ratios for women with three or more births, in comparison with nulliparae, were 0.6 for serous, 0.4 for endometrioid, 1.0 for mucinous and 0.7 for other histological types of ovarian cancer. Family history of ovarian/breast cancer was associated to the risk of all ovarian cancer types, except mucinous ones. Selected dietary factors were less strongly directly (meat and starch), or inversely (fish and vitamin E) related to mucinous than to other histological types of ovarian cancer. High occupational physical activity was inversely related to the risk of ovarian cancer, with no heterogeneity across histologies. In conclusion, the association of reproductive factors and of selected dietary habits was weaker for mucinous ovarian cancer than for other histologic types.

Physical Activity and Risk of Ovarian Cancer: Results from the Netherlands Cohort Study (The Netherlands)

OBJECTIVE

To investigate the association between nonoccupational physical activity and the risk of ovarian cancer among post-menopausal women.

METHODS

The Netherlands Cohort Study on Diet and Cancer consists of 62,573 women aged 55-69 years at baseline. Information regarding baseline nonoccupational physical activity and history of sports activity was collected with a self-administered questionnaire in 1986. After 11.3 years of follow-up, 252 cases of invasive epithelial ovarian cancer were available for case-cohort analysis.

RESULTS

In multivariate analysis and compared to women who spent less than 30 min per day on physical activity, the rate ratios (RRs) of ovarian cancer for women who spent up to 60, 90 and >90 min per day were 0.78, 0.86 and 0.72, respectively (95% confidence interval (CI) for the top category, 0.48-1.06; p-trend, 0.15). Women who spent more than 2 h per week on recreational biking and walking had a reduced risk of ovarian cancer (RR = 0.65; 95% CI: 0.41-1.01) compared to women who never participated in recreational biking or walking.

CONCLUSIONS

These data suggest a modest inverse association between moderate physical activity and ovarian cancer risk. Vigorous physical activity was not associated with ovarian cancer risk.

Prospective study of physical activity in different periods of life and the risk of ovarian cancer

Only few studies have assessed the role of physical activity in the etiology of ovarian cancer, and the results have been inconclusive. We studied associations between physical activity and risk of ovarian cancer in 96,541 women aged 30-49 at enrollment in a prospective study in Norway and Sweden. Participants reported physical activity level at ages 14, 30 and at enrollment, and participation in competitive sports. Complete follow-up through 2001/2002 was achieved by linkage to national registries. The relation between physical activity and ovarian cancer incidence was assessed using multivariate Cox proportional hazard models. During an average 11.1 years of follow-up, there were 264 ovarian cancer cases (including 81 borderline tumors) diagnosed at a mean age of 49 years. Highly physically active women at cohort enrollment had a similar risk of ovarian cancer as women reporting no activity (multivariate relative risk RR = 1.08, 95% CI 0.53-2.18). Physical activity at age 30 or at age 14 did not either afford any protection from ovarian cancer, nor did a consistently high level of activity from younger ages until enrollment. Results were similar for invasive and borderline tumors, and for different subgroups of women classified according to other known risk factors for ovarian cancer. In our study of primarily premenopausal women, physical activity at different ages did neither reduce nor increase risk of ovarian cancer. In the context of the inconsistent scientific literature, our findings probably reflect that physical activity is not causally related with ovarian cancer.